(a) Technical Field
The present disclosure relates generally to wirelessly charging electric or hybrid electric vehicles, and more particularly, to aligning a vehicle with a wireless charging assembly.
(b) Background Art
Recently, technology relating to electric vehicles (EVs) and hybrid electric vehicles (IIEVs) has been rapidly developing. EVs and IIEVs are powered, at least in part, by electricity, and these vehicles often collect and store electricity, or in other words, are charged, from off-vehicle sources. As such, various methods of charging EVs and IIEVs have been explored. In particular, techniques for wireless charging, or inductive charging, have been the subject of considerable research.
Wireless charging, as opposed to wired charging, improves durability and longevity of the charging components by limiting contact and exposure of the components, increases safety by concealing potentially dangerous wires and connection interfaces, and enhances versatility by allowing charging stations to be implemented in a variety of ways (e.g., as a portable charging pad, embedded in a parking lot or road, etc.). To this end, wireless charging relies on an electromagnetic field to transfer energy between a charging station (e.g., wireless charging assembly) and an electrical device, such as a smart phone, a laptop, or an electric vehicle, as in the present case. Energy is sent through an inductive coupling formed between the wireless charging assembly and the device. Typically, an induction coil in the wireless charging assembly (e.g., primary coil) uses electricity, often provided from the power grid, to create an alternating electromagnetic field. An induction coil in the electrical device (e.g., secondary coil) may then receive power from the generated electromagnetic field and convert it back into electrical current to charge its battery. As a result, the primary and secondary induction coils combine to form an electrical transformer, whereby energy can be transferred between the two coils through electromagnetic induction.
Notably, a key element of successful wireless energy transfer typically requires that the wireless charging assembly and the electrical device be located within reasonable proximity to one another. That is, with respect to the present case, the secondary coil installed in the EV or HEV must be satisfactorily aligned with the primary coil of the wireless charger assembly, in order for the vehicle to be effectively charged. Though recent methods, such as resonant inductive coupling, allow for the charging assembly and electrical device to be spaced further from each other, energy transfer efficiency can suffer when using such techniques. Generally speaking, as the primary and secondary coils are spaced further apart, energy loss increases and charge efficiency decreases.
Currently, proper alignment of the receiving coils installed in an EV or HEV with a wireless charging assembly can be aided through the use of radio-frequency identification (RFID) technology. However, such technology can be too expensive for widespread use. Moreover, less costly techniques, such as magnetic pings sent from the wireless charger, can aid proper alignment, but these techniques can be ineffective.